Extremely rare, the 1978 Heuer Ford Chronosplit RS Motorsport is the kind of piece that watch collectors dream about. Designed to look like spark plugs, the battery covers on the front of the watch require a special tool, and the upper LCD panel features a Ford logo. Amazingly, there's a fully-functioning one for sale, complete with its box, original papers, the original battery tool (and the May 1978 issue of the German "Auto Motor und Sport" Magazine that with an ad for it), from 70s-watches.com for the price of Â£3,800.